Three new studies raise brand-new environmental dilemmas.

Illuminating answers to environmental questions.
April 6 2010 7:05 AM

New Studies, New Questions

Three recent reports make sustainable consumption more complicated.

Illustration by Mark Alan Stamaty. Click image to expand.

This week, the Lantern takes a break from answering your green lifestyle questions to report on three studies that raise brand-new environmental dilemmas.

Is meat less of a climate-change culprit than we thought?
One of the Lantern's frequent tips is to cut back on your meat intake for the sake of the planet. But according to Frank Mitloehner, a researcher from the University of California-Davis, that advice is hogwash.

Mitloehner takes exception to the widely cited claim that livestock are responsible for 18 percent of the world's anthropogenicgreenhouse gas emissions—more than the entire transportation sector. That assertion come from a 2006 paper from the U.N.'s Food and Agricultural Organization and has been cited by everyone from Paul McCartney to Rajendra Pachauri, the head of the IPCC (not to mention the Lantern herself), as a reason to reduce our consumption of animal products.

Mitloehner is skeptical about that 18 percent figure but doesn't claim that it's wrong, per se. It just doesn't apply to the United States: According to the EPA's inventory, transportation accounts for 26 percent of America's greenhouse gas emissions, whereas livestock's share is a measly 2.8 percent. Therefore, he concludes, Americans cutting back on meat and dairy would bring relatively small benefits.

But given what a big pie we're talking about, even a tiny slice is pretty substantial: 2.8 percent equals 198 million metric tons of carbon-dioxide equivalent—or roughly all of Venezuela's energy-related CO2 emissions in 2008. Other commenters have pointed out that American livestock are actually responsible for more than 198 million metric tons of CO2-equivalent, since the EPA's figure includes only direct emissions from the animals (i.e., from their manure, burps, and farts). Furthermore, climate change is only one of the ways cows, pigs, and chickens affect the planet—land and water pollution are big concerns, too.

So by all means, we should be looking for ways to reduce our use of fossil fuels for electricity, heating, and transportation, as Mitloehner argues. But curbing our meat intake—particularly red meat, which is so much more resource-intensive than nearly all other food products—still seems like sound environmental advice to the Lantern, even if American farm animals aren't quite the global warming bogeymen we previously imagined.

Mitloehner does have a point when he argues that we should drop the "bigger than the transportation sector" meme, pending better research. Though the FAO researchers tallied emissions from every part of the livestock life cycle, the transportation figures they used considered only tailpipe emissions. If they had done a similarly comprehensive analysis that included the production of the gasoline, vehicles, and roads, the world's cars could very well turn out to have a larger carbon footprint than its cows.

The FAO is currently preparing a more detailed analysis of livestock's carbon footprint for the end of the year—a report that should include a comparison of the impacts associated with carnivorous and vegetarian diets, plus a breakdown of the emissions from different animals, farming systems, and regions. When that happens, you can be sure the Lantern will be reading with interest—and reporting back to you.

Are we outsourcing our greenhouse gas emissions?
When we talk about a nation's carbon footprint, we generally mean the emissions produced within its borders—i.e., whatever gets pumped out from its power plants, factories, and so forth. But because goods produced in one country may be used in another, tallying up direct emissions may not be the best way of assigning responsibility for climate change. So two researchers from the Carnegie Institution of Washington, Steven J. Davis and Ken Caldeira, decided to construct an alternate emissions inventory—one that reflected countries' consumption patterns as opposed to just their production practices. 

In their study published last month in Proceedings of the National Academy of Sciences, Davis and Caldeirafound that nearly one-quarter of the world's energy-related carbon dioxide emissions—or 6.2 billion metric tons—is actually "traded" between countries, largely in the form of products moving from the developing world to wealthier nations.

America is the world's leading netimporter, bringing in nearly 700 million metric tons in 2004, or 10.8 percent of our overall consumption-related emissions. The average American "consumes" 22 metric tons of CO2 annually, of which 2.4 tons are actually emitted abroad. (Some countries in Europe import more than 30 percent of their overall emissions and more than 4 tons for each citizen.)

Meanwhile, China is the world's leading net exporter: 22.5 percent of its production emissions were related to goods that wound up outside the Middle Kingdom. China and India may now be among the world's biggest CO2 emitters, but the people in those countries aren't entirely to blame. As the world continues its struggle to reach a global consensus on climate change, that's a point developed nations would do well to keep in mind.

Can personal choices really make a big difference?
The Natural Resources Defense Council thinks so. The environmental action group just released a report, in conjunction with theGarrison Institute's Climate, Mind, and Behavior Project, that outlines 14free or low-cost things individuals can do that would collectively eliminate a billion tons of carbon dioxide equivalent—or almost 15 percent of America's total emissions.

It's not a particularly surprising list to anyone who's even mildly committed to green living. The report recommends keeping your vehicle properly maintained, using your clothes dryer sparingly, and replacing incandescent bulbs with compact fluorescent ones. (If every household replaced six interior bulbs and one exterior bulb, NRDC calculates that the country would avoid 30 million metric tons of CO2-equivalent.)

A billion-ton reduction is a good carrot but to achieve those kinds of cuts, every single American would have to implement all the changes NRDC suggests. And the head of the NRDC has been quick to note that personal behavior is only one part of the overall equation. But as a simple, straightforward list of the low-hanging fruit we should all be focusing on, the Lantern thinks it represents a pretty solid action plan.

Is there an environmental quandary that's been keeping you up at night? Send it to, and check this space every Tuesday.



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